JPS6122354A - Production of toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To obtain easily a toner for developing an electrostatic charge image having a small grain size and low internal moisture content by dispersing a toner compsn. into an aq. soln. contg. finely granular calcium triphosphate and common salt and subjecting the same to suspension polymn. CONSTITUTION:An alkali metallic salt of phosphoric acid (e.g., sodium phosphate) is dissolved in 60-120-times water and thereafter calcium chloride is added to the soln. to effect the reaction expressed by the formula, thereby formong the calcium triphosphate and common salt having about <=0.35mum particle size, a large surface area and excellent dispersion stability. The toner compsn. consisting of a polymerizable monomer (e.g.; styrene), coloring agent (e.g.; carbon black), polymn. initiator (e.g.; benzoyl peroxide) and necessary additives such as charge adjusting agent is dispersed into the soln. and is subjected to the suspension polymn., by which the intended toner for developing the electrostatic charge image is obtd.

Description

[Detailed description of the invention] The present invention relates to a method for producing a toner for developing electrostatic images.

Regarding toners for developing electrostatic images in electrophotography and the like, various methods of manufacturing toners using suspension polymerization methods have been proposed in place of the conventional so-called pulverization methods.

The suspension polymerization method is generally a method in which a toner composition containing a colorant, etc., is polymerized in a polymerizable monomer by suspension polymerization, and a stable dispersion state of the toner composition is obtained. Therefore, a dispersant is usually included in the dispersion medium.

As the dispersant (dispersion stabilizer), generally used are water-soluble polymer substances such as polyvinyl alcohol and gelatin, and fine powders of poorly water-soluble inorganic substances such as barium sulfate and calcium carbonate.

However, it is generally difficult to remove these dispersants, and the former is particularly difficult to remove because the aqueous solution is viscous, remaining on the toner surface and inhibiting triboelectric charging characteristics. death.

This method has the disadvantage of extremely degrading image quality.

The present invention has an excellent effect of maintaining dispersion stability because the particle size of the dispersant is small and the surface area is large, reducing the amount of dispersant used, reducing the amount of acid treatment and the amount of washing water, and treatment with a small amount of dilute acid. The dispersant can be easily removed to the outside of the thread by this process, and therefore, the sea coloring agent such as carbon black in the toner composition is not damaged by this process (and water is removed from the pores of the toner circle). This was completed as a result of intensive studies with the aim of providing a method for producing toner for developing electrostatic images with small particle size and low internal moisture content. It is.

The present invention involves producing tricalcium phosphate and by-product salt, particularly common salt, in a toner production system in which water is present in an amount of 60 to 120 times the amount of salt, and then directly dispersing the toner composition and carrying out suspension polymerization. The present invention relates to a method for producing a toner for developing an electrostatic image.

In the method of manufacturing toner by suspension polymerization, it is quite conceivable to use tribasic calcium phosphate as a dispersant as in the present invention, and Japanese Patent Application Laid-open No. 56-130762 describes
The use of addition products of sodium phosphate and calcium chloride as dispersants has been described.

However, when such tricalcium phosphate (hereinafter referred to as TCiP) is used as a dispersant, its particle size is a problem; different particle sizes have different surface areas, and depending on the particle size, it may be difficult to treat with dilute acid. The processing amount of T(
The absolute amount of 3P is also determined.

Generally, the toner particle size is normally required to be 5 to 20μ, so when using general TCP as a dispersant,
In order to maintain a stable dispersion state, at least 10 to 209 is necessary for 100 g of toner production, and 1
In order to finally completely remove 20 g of HG from the system, an excess amount of HG/ is required, and a smaller amount (twice as much) is required.

The particle size of commercially available TCP is small, 0.
It is about 35 μIB, which is a huge amount from now on.
'i, and even though the above-mentioned publication describes the use of an addition product of tribasic sodium phosphate and calcium chloride as a dispersant, In the case of TCP, the particle size also varies, and similarly an excessive amount of He/ is required.

When using an excessive amount of ICi/ as described above, this HeI! It is clear that the toner is eluted from the toner due to the addition of an excessive amount of He/, followed by <H20 cleaning, etc., which leads to high costs.

From this point of view, the present invention increases the amount of water when producing %TCP by 60 to 120 times the amount of salt, which is the raw material for producing TCP.
weight, the same applies hereafter]. Examples of this salt include sodium phosphate and potassium phosphate, with sodium phosphate being preferred. As a result, TCP with a particle size of 0.35 μm or less, preferably 0.2 μm or less, especially 0.1 μm or less, a large surface area, and a good dispersion stabilizing effect can be used, for example.

It can be obtained according to the following equation.

2 Na PO+3 Gap/ −+ (3a3(PO
4) 2+6 Nap/When the amount of water is 60 times or less relative to the salt, the reaction occurs instantaneously.

TCP undergoes furochelation, and the TCP particle size is 0.5 to 5 μm, making it impossible to obtain the desired particle size of 0.1 μm or less, and also unable to obtain the required toner particle size. This results in a lack of dispersion stability;
If the ratio is 20 times or more, even if the desired TOP particle size is obtained, the absolute amount is insufficient, resulting in the resulting toner particle size being too large or the monodispersion becoming unstable, resulting in toner agglomeration. bring about.

The temperature of the above reaction is not limited (1) It is usually carried out at room temperature to 50°C.

As mentioned above, the reaction for producing TCP is carried out using salts such as Na,
It is a production reaction between PO4 (hereinafter explained using Na3PO4 as an example) and calcium chloride.1For example, it is a reaction between trisodium phosphate dodecahydrate and calcium chloride dihydrate, and salt (Nap/) is produced as a by-product. .

Normal TCP is Napl! However, the present invention is characterized in that this Nap/ffi is allowed to exist and used as it is.

That is, in the present invention, the by-product Nap/ has various advantages in toner production, and adds to the uniqueness of the present invention.

For example, styrene, paramethylstyrene, or acrylic acid, butyl acrylate, methyl methacrylate, etc., which provide softening properties to the toner, are used as polymerizable monomers (seven polymers) in toner compositions. It is relatively water soluble.

This has an adverse effect on the dispersion system during toner production, and also has an adverse effect on costs, such as the need to add these monomers in an amount greater than the theoretical amount. Further, since the toner produced by the suspension polymerization method is an aqueous toner, it contains water in the pores of the toner, which also has the adverse effect of reducing the amount of charge.

The presence of Ntol in the present invention has a salting-out effect and a function of removing water from the pores in the toner, and was able to bring about good results in the production of toner by suspension polymerization.

In the above reaction, a surfactant may be added (in this case, an anionic surfactant is used as the surfactant to facilitate the production of TOP with a desired particle size and promote the dispersion effect of TCP). can do.

Specific examples of anionic surfactants include sodium dodecylbenzenesulfonate.

Another feature of the method of the present invention is that calcium tertiary 11 phosphate and common salt are produced in a toner manufacturing system.

Next, preferred embodiments of the method of the present invention will be shown.

The method of the present invention involves the use of particles of 0.05 to 10.0 mm in size produced by the reaction of trisodium phosphate and calcium chloride in the presence of an appropriate amount of water.
By using TCP and Nhol in the form of fine particles of 1 μm or less as they are, dispersing the toner composition, and performing suspension polymerization, it is possible to obtain a toner with a small particle size and low internal water content. The generation of TCP and Nap/, dispersion of the toner composition, and suspension polymerization are performed in a series of operations. That is, Na3PO4 and Ga, which are raw materials for TCP, are contained in an appropriate amount of water.
C/2 and a toner composition into the aqueous system,
Stir to form toner oil droplets and perform suspension polymerization.

The toner composition includes, for example, a colorant, a polymerizable monomer, a charge control agent, a polymerization initiator, and other additives.

A specific example of a colorant is carbon black.

Examples of polymerizable monomers include primary monomers, which can be used alone or in combination in copolymerization.

Styrene, 1o-71talstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tθrt butylstyrene%p
- Styrenic monomers such as phenylstyrene, 0-chlorostyrene, m-chlorostyrene, p-chlorostyrene: methyl acrylate, ethyl acrylate, acrylic acid n
-Butyl, inbutyl acrylate, dodecyl acrylate, stearyl acrylate, acrylic Wk2-ethylhexyl, ethyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, inbutyl methacrylate, Mn-octyl methacrylate, dodecyl methacrylate , acrylic acid such as 2-ethylhexyl methacrylate, stearyl methacrylate, or methacrylic acid
Acid monomers: ethylene, propylene, butylene, vinyl chloride, vinyl acetate, acrylonitrile.

As the charge control agent used for the purpose of charge control, dyes that are commonly called charge control agents can be used, and dyes for polarity or θ polarity can be used depending on the purpose.

Examples of the polymerization initiator (radical initiator) include peroxide-based initiators such as EVA, benzoyl peroxide, lauroyl peroxide, and stearyl peroxide, and 2.21-azobisinbutyronitrile.
2'-Azobis-(2°4-dimethylvaleronitrile)
An azobis-based initiator such as is used.

As other additives, for example, low molecular weight olefin polymers known as mold release agents, magnetic colorants, etc. can be used.

As described above, according to the present invention, the particle size of TOP is as small as 0.35 μm or less, preferably 0.2 μm or less, particularly 0.1 μm or less, and therefore the surface area is large. Therefore.

Use of this TCP can greatly contribute to maintaining dispersion stability.

As is well known, the surface area of TCP affects the maintenance of dispersion stability, and stability increases in proportion to the square of the particle size.

Furthermore, since the surface area of TOP is large, the absolute amount of 5TOP can be reduced, and accordingly, the amount of (He/) and the amount of H20 cleaning can be reduced.

According to the present invention, Na0j' is made to coexist with TCP (therefore, even if a water-soluble monomer is used, the salting out effect of Nhol will cause the dispersion system to be adversely affected during toner production. There is nothing to do.This NapI again!
The presence of water in the toner (J:D,) removes water from the pores in the toner, so the pores of the toner contain water, which reduces the amount of charge. .

According to the present invention, a toner having a toner particle size of 1 to 20 μm can be obtained.

Normally, toner is required to have a particle size of 5 to 20 μm, but it is generally difficult to obtain a particle size of 10 μm or less when TCP is used as a dispersant. However, in the present invention, a toner having a fine particle size of 8.56 μm, which is also shown in Examples, was obtained.

Next, the present invention will be explained with reference to Examples and Comparative Examples.

Example 1 In a 500 ml beaker, 200 ml of water and 9 were mixed with sodium phosphate 5.14.9°, calcium chloride 2.98.9°, dodecyl while stirring at 160 r, p, m with a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). A toner composition (carbon black (n-4oo
n (Cabot) [) ] 10 parts, 70 parts of styrene, n
Add 70g of butylmequaacrylate (30ff, S-31 (manufactured by Orient Chemical Co., Ltd.), 2 parts, AlBN 2 parts), rotate at 600 Or, pom, for 30 seconds to disperse the toner composition and create stable oil droplets. The reaction was completed in a Gen500 autoclave equipped with a stirring blade at a reaction temperature of 71°C and a reaction time of 6 hours.

Next, HO/ was added to this to replace TCP with water-soluble calcium chloride, and the mixture was discharged from the system. The obtained toner particle size was 8
．． It was 55μ. Further, the internal moisture content of the toner was 0.01% or less.

In order to measure the particle size of TCP in the present invention, a system containing no toner composition was synthesized purely under the conditions below TOPt of the present invention.

100 M of water was added to a 200 ml beaker, 2.579 g of sodium phosphate was dissolved at room temperature while stirring, and calcium chloride LA q I was added to maintain the reaction for 30 minutes. After 50 minutes, the precipitated TCP was separated from unreacted sodium phosphate or calcium chloride and by-produced sodium chloride by centrifugation, and then dried. 1.05g
of TCP was obtained. The particle size of the produced TCP was measured using a Coulter counter and found to be 0.09 μm.

Comparative Example 1 A toner composition similar to that of Example 1 was prepared. 500
Pour 200 mA of water into a 1 m beaker and use a T made by Taihei Kagaku Co., Ltd.
Add 2.19 of CP (particle size Q, 55tirn) and 0.01261 of sodium dodecylbenzenesulfonate to 1
It was used as a dispersion medium. 709 g of a toner composition was added to this dispersion medium, and the same dispersion and suspension polymerization as in Example 1 was carried out.

The resulting toner particle size was 13.8μ. Further, the internal moisture content of the toner was 0.1%.

Claims (1)

[Claims] Tricalcium phosphate and common salt are produced in a toner production system in which water is present in an amount of 60 to 120 times as much water as alkali metal phosphate (hereinafter simply referred to as salt), and the toner composition is dispersed and suspended in the system. A method for producing a toner for developing electrostatic images, characterized by carrying out polymerization.